The employment of gas arc lamps and especially of fluorescent lamps is common practice in many industrially and economically oriented fields due to their higher efficiency when compared to filament lamps and due to illumination characteristics that are widely variable by selecting the fluorescent coating. In particular, for applications in which not only high efficiency but also a stable, i.e. flicker-free, illumination or a continual adjustment of the luminescence of a gas arc lamp is required, electronic ballast devices are often used that enable an operation of the gas arc lamp at high frequencies in the range of approximately 20 kHz to 50 kHz. Consequently, the flicker may be avoided or is no longer perceivable contrary to gas arc lamps that are merely operated at the grid frequency by means of a choke, wherein an appropriate control of the electronic ballast device enables the variation of the illumination intensity within a wide range.
The increasing employment of electronic ballast devices, however, entails an increased transmission of interfering signals that are generated by the switched operation of the switching elements—mostly MOSFETs- or bipolar transistors—used in the electronic ballast device. Moreover, the application of electronic ballast devices causes a significant non-sinusoidal current extraction from the grid, which leads to a remarkable supply of upper harmonic waves into the grid, thereby resulting in an undue loading of the grid. Consequently, legislators have issued corresponding guidelines with respect to the creation of upper harmonic waves of electronic ballast devices, especially in the power range up to 1000 W, which may not be exceeded. For this reason, a multiplying boost converter precedes the electronic ballast device, which is also referred to as a “power factor regulator,” so as to maintain the power factor at approximately 1, i.e., to extract the current from the grid in a substantially sinusoidal form and in phase with the grid voltage.
The power factor regulator generally requires a further switching element and an inductor, thereby causing a significant increase in the number of circuit elements. Furthermore, with reasonable effort typically an efficiency of the power factor regulator of 95% at most is achievable, so the total efficiency of the system comprised of the power factor regulator, the electronic ballast device and the gas arc is reduced. The boost converter used in the power factor regulator operates in a switched mode and contributes to a further increase of the interference radiation, thereby requiring great effort to filter the interference radiation and necessitating expensive metal housings.